The brilliant Frank Lloyd Wright designed his masterpiece to straddle a forest waterfall, and the resulting home, built as a bucolic escape for a Pittsburgh department store owner, where the river’s rush is always audible, has been an architectural icon ever since. Admission $20

Created in 1955 to keep post-war businesses from relocating, Pittsburgh's Mellon Square not only accomplished that, but continues to attract city dwellers and tourists with live concerts and performances.